identified as 19-year-old dzhokhar tsarnaev. he is considered armed and extremely dangerous, something that goes without saying at this point. born in kyrgyzstan and they both apparently moved here to the united states with their family as around 2002. as pete williams reports, their father worked in chechnya, which would leave one to believe that they lived for a while in chechnya. >> police are going door to door trying to find him. they are warning people to stay in their homes and not to let anybody in unless they are uniformed police officers. we have twitter photos that really show exactly how grave the situation and how people's lives in watertown and boston and newton and all the surrounding towns are being turned upside down. as you can see, s.w.a.t team members literally climbing over a shed in what looks like a lovely neighborhood. it all began, apparently, when the suspect tried to rob a 7-eleven, two of them, and then shot and killed, as i mentioned, an m.i.t. police officer. they shot him in the head. carjacked a m